Blower and aspirator tube assembly



May 6, 1969 N, PRATT 3,442,092

BLOWER AND ASPIRATOR TUBE ASSEMBLY Filed Dec. 4, 1967 INVENTOR JOHN N. DraAr-r ATTORNEYS m usc. llifwwce United States Patent O U.S. Cl. 62-279 6 Claims ABSTRACT OF THE DISCLOSURE A centrifugal blower of the scroll type producing an air stream, and having an aspirator tube in a wall thereof with one end communicating with a source of fluid and the other end located in the air stream to aspirate a portion of the liuid into the air stream. The blower and aspirator tube assembly may be employed -in an air conditioner to aspirate liquid condensate collected from the evaporator into a condensing air stream produced by the blower for re-evaporation of the condensate lby thermal exchange with the condenser.

The present invention relates in general to comfort conditioning systems such as air conditioners, dehumiditiers, and the like, and more particularly to air conditioning apparatus having means for disposing of moisture condensate produced during oper-ation of the apparatus.

In the process of cooling air for comfort conditioning, the air being cooled is usually reduced in temperature below its dew point, resulting in the condensing of moisture from the air being processed. This moisture removal is referred to as latent cooling which takes place at constant temperature as compared to sensible cooling which is measured by the change in temperature of the air. Latent cooling is approximately one thousand B.t.u.s for each pound of water condensed.

Latent cooling is very desirable and is sought for rather than avoided. Some air conditioning apparatus is especially designed to lower the air temperaturebelow its final desired temperature, then reheat to the desired ternperature to further dry the air `and increase the ratio of latent to sensible cooling. Dry cool air is generally more comfortable than cool air which is more nearly saturated with moisture. l

While the process of removing water from air is easily accomplished by cooling, means for disposing of the condensed water present practical problems which sometimes require costly drain structures. Drain devices are frequent sources of trouble from plugging with dirt washed from the air or -mold organisms which grow in the water. Where gravity drains are not feasible, mechanical pumps are sometimes required.

Various mechanical devices have been used to project condensed water against the warm surfaces of condensing coils or against the warm shell of the compressor. Slinger rings around the outer periphery of propeller type condensing air fans are common devices of this type. These are effective, ibut sometimes a source of trouble. I have found centrifugal type fans to be superior to propeller fans from the standpoint of compactness, quietness, etliciency and ability to overcome greater resistance to liow.

With a scroll enclosed centrifugal fan, a rotating slinger ring cannot be used to pick up the condensate and discharge it into the air stream. I have discovered, however, that it is possible to pick up the water by means of a more desirable method utilizing the velocity pressure of the high velocity stream of air immediately adjacent the inner face of the fan scroll as the source of energy to aspirate the water from a point of accumulation outside rice the fan housing and discharge it into the air stream leaving the fan.

The design principle of this invention is that where the velocity pressure at the aspirator is greater than the diierence in static pressure existing without and within the fan scroll, liquid or gas will ow into the aspirator tube and discharge into the air stream.

Where:

Pv=Velocity pressure of air flowing across aspirator Ps=Static pressure inside blower Pa=Static pressure surrounding blower With relatively fixed condition of air flow, the blower can be readily designed to assure the pressure conditions required to cause flow inward through the aspirator. For widely variable conditions of air ow means such as an adjustable vane may be mounted inside the scroll to regulate the velocity of the air passing over the aspirator to sutiiciently high velocity to overcome the difference between Ps and Pa.

An object of the present invention is the provision of improved and more reliable means for disposing of moisture condensate from air conditioning apparatus.

Another object of the present invention is the provision in air conditioning apparatus of a scroll type blower or centrifugal fan for directing a high velocity air stream through the condenser coils of air conditioner apparatus, having aspirator tube means associated therewith and communicating with trough or drain pan in which liquid condensate from the evaporator is collected to withdraw the `condensate into the tube and spray it into the air stream for evaporation and discharge from the apparatus as water vapor,

Other objects and advantages of the present invention will become more apparent to those persons skilled in the art, from the following description when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a diagrammatic sectional view of a packaged air conditioner using the present invention, and

FIGURE 2 is a sectional view of a typical blower housing having an aspirator tube associated therewith in accordance with one form of the invention.

Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, and particularly to FIGURE l, there is illustrated `a packaged air conditioner, generally indicated by the reference character .10, embodying the present invention. This packaged air conditioner consists essentially of a refrigerant compressor 11 of conventional construction, having a hot gas conduit 12 extending from the discharge side thereof for conveying the hot gaseous refrigerant from the compressor 11 to the condenser coil 13 of conventional construction. The condenser coil 13, for example, may be of the conventional air cooled type having a sinuous array of tubes and associated iins to facilitate thermal exchange between the refrigerant flowing within the tubes and the surrounding -air to efect condensation of the hot gaseous refrigerant to liquid state. A high pressure liquid refrigerant conduit or line 14 connects the condenser outlet to a conventional restrictor 15, which is connected by a low pressure refrigerant line or conduit 16 to the inlet of the evaporator .17. The evaporator 17 is likewise of conventional construction, the outlet of which is connected by low pressure suction conduit 18 to the suction side of the compressor 11. Thus, refrigerant compressed by the compressor 11 is conveyed as hot gaseous refrigerant through the hot gas line 12 to the condenser coil 13, where the refrigerant condenses to liquid form and is conveyed through the high pressure liquid line 14 to the restrictor 15. The refrigerant is admitted in metered quantities from the restrictor 15 through the low pressure refrigerant line 16 to the evaporator 17 to extract heat from the zone surrounding the evaporator 17 and return as gaseous refrigerant through the suction line 18 to the compressor 11. These parts make up the sealed refrigerant circuit.

Air for cooling the hot refrigerant gas in the condenser 13 to its condensing temperature is supplied by fan 19 from an ambient air source (not shown). The spent hot air is discharged in conventional manner to the atmosphere through an outlet opening, not shown.

The air to be cooled is drawn from the conditioned space by fan 20 and forced through evaporator coil 17 in which it is cooled and from which it is returned to the conditioned space through an opening or conduit 20a.

Liquid condensate, indicated at 21, condensed from the cooled air owing through the evaporator 17 drains from the surface of coil 17 into leak tight drain pan 22 and ows through ya restricted opening 23 in bulkhead 24. Except for the drain opening 23 located at the extreme lower end, bulkhead 24 isolates the circulating conditioned air from the ambient condensing air surrounding the cornpressor 11 and condenser fan 19.

The condenser fan 19 is a scroll type blower or centrifugal fan having the conventional, generally spiral shaped scroll 25, within which an impeller rotates, having a discharge outlet 26 for discharge of air, for example, through a duct or hood 27 to the condenser coil 13 for flow through the condenser coil and exit externally of the system. The scroll also has the usual circular air inlet 28 in one side thereof for drawing air into the center region within the rotating air impeller. In the lower region of the scroll 19 adjacent the point where the transition from the curved, cylindrical portion of the scroll wall to the tangential straight wall of the outlet 26 occurs, an aspirator tube 29 is inserted into the peripheral wall of the scroll, disposed in such a way as to have an external tube portion 30 extending from the outer wall of the scroll at a desired angle, for example, either approximately parallel to the straight lower wall of the blower outlet 26, as illustrated in FIGURE 2, or at a slightly downwardly inclined angle thereto and opening in a direction opposite the blower outlet, as illustrated in FIGURE l, whereby the lower end of the aspirator tube 29 is immersed at least to some extent in the liquid condensate in the pan 22 provided at the bottom of the apparatus. The opposite end or internal tube section 32 of the aspirator tube 29, in the herein disclosed example, extends upwardly into the high velocity air stream existing immediately adjacent the inner face of the scroll wall at approximately the transition from the curved wall to the straight tangential wall of the outlet 26, and has an opening cut in the wall of the internal tube section 32, such as the V notch 33 illustrated in the drawings, to facilitate the aspirating action of the tube 29.

When the condensate level in pan 22 reaches the inlet level of aspirator tu-be 29, water is drawn into the aspirator and sprayed into the owing stream of condensing air as droplets. These droplets are carried into condenser coil 13 where they become heated, evaporate and are discharged as water vapor in the rejected stream of hot condensing air. Any droplets of moisture not evaporated drain from condenser coil 13 into pan 22 from which they re-enter aspirator tube 29 and again enter the ow of condensing air.

As previously mentioned, if the air flow conditions in the zone of the internal tube section 32 vary over a wide range or are inadequate due to the design of the blower to produce a sufficiently high velocity pressure at the tube 29 to provide proper aspirating action, an adjustable vane, as indicated diagrammatically at 34, in FIGURE 2, may be mounted inside the scroll to increase the velocity of the air passing over the internal aspirator tube section 32 to overcome the difference between static pressure existing between the inside and outside of the scroll and produce proper aspirator action.

The blower and aspirator tube assembly of the present invention may also be used to advantage in applications where it is desired to add moisture to air for increasing humidity or to introduce odor controlling or sanitizing chemicals into a moving air stream, by directing the primary air stream to be treated through the blower scroll prior to admission to the space to be served and immersing the exterior section 30 of the aspirator tube 29 in a water or appropriate chemicals in liquid form. Similarly, two relatively different sized air streams may be conveniently moved by a single blower with the present invention, as where it is desired to introduce a proportion, such as 10% fresh outside air into a recirculated air stream, by conveying the recirculation air through the blower scroll 25 and communicating a duct leading to fresh outside air with the external aspirator tube section 30 to draw the outside air into the recirculation air stream. Fluid and gaseous fuel may also be mixed with air or oxygen for combustion by the blower and aspirator tube assembly by conveying the air or oxygen supply through the blower scroll 25 and communicating the exterior aspirator tube section with the fluid or gaseous fuel supply.

From the foregoing detailed description it will Ibe understood that there are a number of changes, adaptations and modifications of the present invention which come within the province of those skilled in the art. However, it is intended that all such variations not departing from the spirit of the invention -be considered as within the scope thereof as limited solely by the appended claims.

I claim:

1. In an air conditioning system having a refrigerant circuit including a compressor, an air cooled condenser and an evaporator; the improvement in means for disposing of liquid condensate formed on external coil surfaces of the evaporator comprising a centrifugal blower having an inlet communicating with a condensing air supply and a scroll housing and impeller means for producing a condensing air stream within the scroll housing and discharging the same through the condenser in thermal exchange relation with refrigerant in the condenser to condense the refrigerant, means for receiving liquid condensate from coil surfaces of the evaporator and conveying the same to an accumulation zone externally adjacent said scroll housing, aspirator tube means extending through a wall of said scroll housing having an outer open end in said accumulation Zone and an inner open end located in a region in said scroll housing where the velocity pressure of the condensing air stream is sufficiently greater than the static pressure difference existing within and without the housing to aspirate liquid condensate from said accumulation zone and entrain the same in droplet form into the condensing air stream for discharge therewith through said condenser and evaporation thereof by heat rejected by condensation of refrigerant in the condenser, and said blower including adjustable vane means within said scroll housing for directing the condensing air stream therein to increase the velocity of condensing air passing about the inner open end of said aspirator tube.

2. Apparatus as defined in claim 1, wherein said scroll housing has a substantially cylindrical outer wall portion over its major circumferential extent merging into a substantially straight wall portion extending substantially tangentially from said cylindrical wall portion and dening one wall of an outlet duct of said scroll housing, said blower producing velocity pressure conditions within said housing immediately adjacent the transition from said cylindrical wall portion to said straight wall portion greater than the difference between static pressure within and without said scroll housing, and said inner open end of said aspirator tube being located adjacent the inner surface of the outer wall of said scroll housing substantially at said transition.

3. Apparatus as defined in claim 2, wherein said means for receiving liquid condensate comprises an upwardly opening drain pan extending from beneath said evaporator to said accumulation zone adjacent and beneath said blower oriented to collect liquid condensate gravity discharged from the evaporator for tlow to said accumulation zone, said outer end of said aspirator tube depending into said drain pan for immersion into liquid condensate at said accumulation zone to aspirate the liquid condensate into said tube.

4. Apparatus as defined in claim 1, wherein said means for receiving liquid condensate comprises an upwardly opening drain pan extending from beneath said evaporator to said accumulation zone adjacent and beneath said blower oriented to collect liquid condensate gravity discharged from the evaporator for flow to said accumulation zone, said outer end of said aspirator tube depending into said drain pan for immersion into liquid condensate at said accumulation zone to aspirate the liquid condensate into said tube.

5. Apparatus as defined in claim 4, wherein said drain pan includes a portion extending from beneath said condenser to said accumulation zone for receiving liquid condensate gravity discharged from external coil surfaces of the condenser and return of the same to said zone.

6. Apparatus as defined in claim 4, including a casing for the air conditioning system having an internal partition therein defining a rst compartment for said evaporator and flow of circulating conditioned air therethrough, and a second compartment for said compressor and condenser and blower for circulation of condensing air therethrough, said partition having an opening in the lower end thereof for passage of said drain pan therethrough from said rst compartment to said second compartment, said opening having its upper edge immediately above a preselected liquid condensate level in said drain pan to permit flow of liquid condensate between said compartments while substantially isolating the circulating conditioned air from the condensing air.

References Cited UNITED STATES PATENTS 2,495,002 1/1950 Hart 62--280 2,710,510 6/ 1955 Roseman 62-280 3,045,449 7/ 1962 Durdle 62--279 3,159,984 12/ 1964 Eberhart 62--279 WILLIAM I. WYE, Primary Examiner.

U.S. C1. X.R. 62--262 

